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<div class="titlepage"><div><div><h4 class="title">
<a name="boost_asio.reference.experimental__make_parallel_group.overload1"></a><a class="link" href="overload1.html" title="experimental::make_parallel_group (1 of 3 overloads)">experimental::make_parallel_group
        (1 of 3 overloads)</a>
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<p>
          Create a group of operations that may be launched in parallel.
        </p>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span>
    <span class="keyword">typename</span><span class="special">...</span> <span class="identifier">Ops</span><span class="special">&gt;</span>
<span class="identifier">parallel_group</span><span class="special">&lt;</span> <span class="identifier">Ops</span><span class="special">...</span> <span class="special">&gt;</span> <span class="identifier">make_parallel_group</span><span class="special">(</span>
    <span class="identifier">Ops</span><span class="special">...</span> <span class="identifier">ops</span><span class="special">);</span>
</pre>
<p>
          For example:
        </p>
<pre class="programlisting"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">experimental</span><span class="special">::</span><span class="identifier">make_parallel_group</span><span class="special">(</span>
  <span class="identifier">in</span><span class="special">.</span><span class="identifier">async_read_some</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(</span><span class="identifier">data</span><span class="special">)),</span>
  <span class="identifier">timer</span><span class="special">.</span><span class="identifier">async_wait</span><span class="special">()</span>
<span class="special">).</span><span class="identifier">async_wait</span><span class="special">(</span>
  <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">experimental</span><span class="special">::</span><span class="identifier">wait_for_all</span><span class="special">(),</span>
  <span class="special">[](</span>
      <span class="identifier">std</span><span class="special">::</span><span class="identifier">array</span><span class="special">&lt;</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span><span class="special">,</span> <span class="number">2</span><span class="special">&gt;</span> <span class="identifier">completion_order</span><span class="special">,</span>
      <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span> <span class="identifier">ec1</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">n1</span><span class="special">,</span>
      <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span> <span class="identifier">ec2</span>
  <span class="special">)</span>
  <span class="special">{</span>
    <span class="keyword">switch</span> <span class="special">(</span><span class="identifier">completion_order</span><span class="special">[</span><span class="number">0</span><span class="special">])</span>
    <span class="special">{</span>
    <span class="keyword">case</span> <span class="number">0</span><span class="special">:</span>
      <span class="special">{</span>
        <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"descriptor finished: "</span> <span class="special">&lt;&lt;</span> <span class="identifier">ec1</span> <span class="special">&lt;&lt;</span> <span class="string">", "</span> <span class="special">&lt;&lt;</span> <span class="identifier">n1</span> <span class="special">&lt;&lt;</span> <span class="string">"\n"</span><span class="special">;</span>
      <span class="special">}</span>
      <span class="keyword">break</span><span class="special">;</span>
    <span class="keyword">case</span> <span class="number">1</span><span class="special">:</span>
      <span class="special">{</span>
        <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"timer finished: "</span> <span class="special">&lt;&lt;</span> <span class="identifier">ec2</span> <span class="special">&lt;&lt;</span> <span class="string">"\n"</span><span class="special">;</span>
      <span class="special">}</span>
      <span class="keyword">break</span><span class="special">;</span>
    <span class="special">}</span>
  <span class="special">}</span>
<span class="special">);</span>
</pre>
<p>
          If preferred, the asynchronous operations may be explicitly packaged as
          function objects:
        </p>
<pre class="programlisting"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">experimental</span><span class="special">::</span><span class="identifier">make_parallel_group</span><span class="special">(</span>
  <span class="special">[&amp;](</span><span class="keyword">auto</span> <span class="identifier">token</span><span class="special">)</span>
  <span class="special">{</span>
    <span class="keyword">return</span> <span class="identifier">in</span><span class="special">.</span><span class="identifier">async_read_some</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(</span><span class="identifier">data</span><span class="special">),</span> <span class="identifier">token</span><span class="special">);</span>
  <span class="special">},</span>
  <span class="special">[&amp;](</span><span class="keyword">auto</span> <span class="identifier">token</span><span class="special">)</span>
  <span class="special">{</span>
    <span class="keyword">return</span> <span class="identifier">timer</span><span class="special">.</span><span class="identifier">async_wait</span><span class="special">(</span><span class="identifier">token</span><span class="special">);</span>
  <span class="special">}</span>
<span class="special">).</span><span class="identifier">async_wait</span><span class="special">(</span>
  <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">experimental</span><span class="special">::</span><span class="identifier">wait_for_all</span><span class="special">(),</span>
  <span class="special">[](</span>
      <span class="identifier">std</span><span class="special">::</span><span class="identifier">array</span><span class="special">&lt;</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span><span class="special">,</span> <span class="number">2</span><span class="special">&gt;</span> <span class="identifier">completion_order</span><span class="special">,</span>
      <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span> <span class="identifier">ec1</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">n1</span><span class="special">,</span>
      <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span> <span class="identifier">ec2</span>
  <span class="special">)</span>
  <span class="special">{</span>
    <span class="keyword">switch</span> <span class="special">(</span><span class="identifier">completion_order</span><span class="special">[</span><span class="number">0</span><span class="special">])</span>
    <span class="special">{</span>
    <span class="keyword">case</span> <span class="number">0</span><span class="special">:</span>
      <span class="special">{</span>
        <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"descriptor finished: "</span> <span class="special">&lt;&lt;</span> <span class="identifier">ec1</span> <span class="special">&lt;&lt;</span> <span class="string">", "</span> <span class="special">&lt;&lt;</span> <span class="identifier">n1</span> <span class="special">&lt;&lt;</span> <span class="string">"\n"</span><span class="special">;</span>
      <span class="special">}</span>
      <span class="keyword">break</span><span class="special">;</span>
    <span class="keyword">case</span> <span class="number">1</span><span class="special">:</span>
      <span class="special">{</span>
        <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"timer finished: "</span> <span class="special">&lt;&lt;</span> <span class="identifier">ec2</span> <span class="special">&lt;&lt;</span> <span class="string">"\n"</span><span class="special">;</span>
      <span class="special">}</span>
      <span class="keyword">break</span><span class="special">;</span>
    <span class="special">}</span>
  <span class="special">}</span>
<span class="special">);</span>
</pre>
</div>
<div class="copyright-footer">Copyright © 2003-2025 Christopher M.
      Kohlhoff<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
      </p>
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